path: root/devices/src/virtio/controller.rs

// Copyright 2017 The Chromium OS Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

//! This module implements the virtio wayland used by the guest to access the host's wayland server.
//!
//! The virtio wayland protocol is done over two queues: `in` and `out`. The `in` queue is used for
//! sending commands to the guest that are generated by the host, usually messages from the wayland
//! server. The `out` queue is for commands from the guest, usually requests to allocate shared
//! memory, open a wayland server connection, or send data over an existing connection.
//!
//! Each `WlVfd` represents one virtual file descriptor created by either the guest or the host.
//! Virtual file descriptors contain actual file descriptors, either a shared memory file descriptor
//! or a unix domain socket to the wayland server. In the shared memory case, there is also an
//! associated slot that indicates which KVM memory slot the memory is installed into, as well as a
//! page frame number that the guest can access the memory from.
//!
//! The types starting with `Ctrl` are structures representing the virtio wayland protocol "on the
//! wire." They are decoded and executed in the `execute` function and encoded as some variant of
//! `WlResp` for responses.
//!
//! There is one `WlState` instance that contains every known vfd and the current state of `in`
//! queue. The `in` queue requires extra state to buffer messages to the guest in case the `in`
//! queue is already full. The `WlState` also has a control socket necessary to fulfill certain
//! requests, such as those registering guest memory.
//!
//! The `Worker` is responsible for the poll loop over all possible events, encoding/decoding from
//! the virtio queue, and routing messages in and out of `WlState`. Possible events include the kill
//! event, available descriptors on the `in` or `out` queue, and incoming data on any vfd's socket.

use std::os::unix::io::{AsRawFd, RawFd};
use std::sync::Arc;
use std::thread;

use msg_socket::{MsgReceiver, MsgSocket};
use sys_util::net::UnixSeqpacket;
use sys_util::{error, EventFd, GuestMemory, PollContext, PollToken};
use vm_control::{MaybeOwnedFd, VmMemoryControlRequestSocket};

use super::{
    remote::{Request, Response},
    Interrupt, InterruptProxyEvent, Queue, VirtioDevice,
};
use crate::{
    pci::{PciAddress, PciBarConfiguration, PciCapability},
    MemoryParams,
};

type Socket = msg_socket2::Socket<Request, Response>;

// TODO: support arbitrary number of queues
const QUEUE_SIZE: u16 = 16;
const QUEUE_SIZES: &[u16] = &[QUEUE_SIZE, QUEUE_SIZE];

struct Worker {
    device_socket: Arc<Socket>,
    interrupt: Interrupt,
    interrupt_socket: MsgSocket<(), InterruptProxyEvent>,

    shutdown: bool,
}

impl Worker {
    fn new(
        device_socket: Arc<Socket>,
        interrupt: Interrupt,
        interrupt_socket: MsgSocket<(), InterruptProxyEvent>,
    ) -> Self {
        Self {
            device_socket,
            interrupt,
            interrupt_socket,
            shutdown: false,
        }
    }

    fn handle_response(&mut self) {
        match self.device_socket.recv() {
            Ok(Response::Kill) => {
                self.shutdown = true;
            }

            Ok(msg) => {
                panic!("unexpected message received: {:?}", msg);
            }

            Err(e) => {
                panic!("recv failed: {:?}", e);
            }
        }
    }

    fn interrupt(&self) {
        use InterruptProxyEvent::*;
        match self.interrupt_socket.recv() {
            Ok(SignalUsedQueue(value)) => self.interrupt.signal_used_queue(value).unwrap(),
            Ok(SignalConfigChanged) => self.interrupt.signal_config_changed().unwrap(),
            Ok(InterruptResample) => self.interrupt.interrupt_resample().unwrap(),

            Err(e) => panic!("recv failed: {}", e),
        }
    }

    fn kill(&self) {
        if let Err(e) = self.device_socket.send(Request::Kill) {
            error!("failed to send Kill: {}", e);
        }
    }

    fn run(mut self, kill_evt: EventFd) {
        #[derive(Debug, PollToken)]
        enum Token {
            Device,
            Interrupt,
            Kill,
        }

        let poll_ctx: PollContext<Token> = match PollContext::build_with(&[
            (&*self.device_socket, Token::Device),
            (&self.interrupt_socket, Token::Interrupt),
            (&kill_evt, Token::Kill),
        ]) {
            Ok(pc) => pc,
            Err(e) => {
                panic!("failed creating PollContext: {}", e);
            }
        };

        while !self.shutdown {
            let events = match poll_ctx.wait() {
                Ok(v) => v,
                Err(e) => {
                    panic!("failed polling for events: {}", e);
                }
            };

            for event in &events {
                match event.token() {
                    Token::Device => self.handle_response(),
                    Token::Interrupt => self.interrupt(),
                    Token::Kill => self.kill(),
                }
            }
        }
    }
}

pub struct Controller {
    kill_evt: Option<EventFd>,
    worker_thread: Option<thread::JoinHandle<()>>,
    socket: Arc<Socket>,
}

impl Controller {
    /// Construct a controller, and initialize (but don't activate)
    /// the remote device.
    pub fn create(
        memory_params: MemoryParams,
        vm_control_socket: VmMemoryControlRequestSocket,
        socket: Socket,
    ) -> Result<Controller, msg_socket2::Error> {
        socket.send(Request::Create {
            memory_params,
            vm_control_socket: MaybeOwnedFd::Borrowed(vm_control_socket.as_raw_fd()),
        })?;

        Ok(Controller {
            kill_evt: None,
            worker_thread: None,
            socket: Arc::new(socket),
        })
    }
}

impl Drop for Controller {
    fn drop(&mut self) {
        if let Some(kill_evt) = self.kill_evt.take() {
            // Ignore the result because there is nothing we can do about it.
            let _ = kill_evt.write(1);
        }

        if let Some(worker_thread) = self.worker_thread.take() {
            let _ = worker_thread.join();
        }
    }
}

impl VirtioDevice for Controller {
    fn debug_label(&self) -> String {
        if let Err(e) = self.socket.send(Request::DebugLabel) {
            return format!("remote virtio (unknown type; {})", e);
        }

        let label = match self.socket.recv() {
            Ok(Response::DebugLabel(label)) => label,
            response => panic!("bad response to DebugLabel: {:?}", response),
        };

        format!("remote {}", label)
    }

    fn keep_fds(&self) -> Vec<RawFd> {
        let mut keep_fds = Vec::new();

        if let Some(ref kill_evt) = self.kill_evt {
            keep_fds.push(kill_evt.as_raw_fd());
        }

        keep_fds.push(self.socket.as_raw_fd());

        keep_fds
    }

    fn device_type(&self) -> u32 {
        if let Err(e) = self.socket.send(Request::DeviceType) {
            panic!("failed to send DeviceType: {}", e);
        }

        match self.socket.recv() {
            Ok(Response::DeviceType(device_type)) => device_type,
            response => {
                panic!("bad response to Reset: {:?}", response);
            }
        }
    }

    fn queue_max_sizes(&self) -> Vec<u16> {
        if let Err(e) = self.socket.send(Request::QueueMaxSizes) {
            panic!("failed to send QueueMaxSizes: {}", e);
        }

        match self.socket.recv() {
            Ok(Response::QueueMaxSizes(sizes)) => sizes,
            response => {
                panic!("bad response to QueueMaxSizes: {:?}", response);
            }
        }
    }

    fn features(&self) -> u64 {
        if let Err(e) = self.socket.send(Request::Features) {
            panic!("failed to send Features: {}", e);
        }

        match self.socket.recv() {
            Ok(Response::Features(features)) => features,
            response => {
                panic!("bad response to Reset: {:?}", response);
            }
        }
    }

    fn ack_features(&mut self, value: u64) {
        if let Err(e) = self.socket.send(Request::AckFeatures(value)) {
            panic!("failed to send AckFeatures: {}", e);
        }
    }

    fn read_config(&self, offset: u64, data: &mut [u8]) {
        let len = data.len();

        if let Err(e) = self.socket.send(Request::ReadConfig { offset, len }) {
            panic!("failed to send ReadConfig: {}", e);
        }

        match self.socket.recv() {
            Ok(Response::ReadConfig(response)) => {
                data.copy_from_slice(&response[..len]); // TODO: test no panic
            }
            response => panic!("bad response to ReadConfig: {:?}", response),
        }
    }

    fn write_config(&mut self, offset: u64, data: &[u8]) {
        if let Err(e) = self.socket.send(Request::WriteConfig {
            offset,
            data: data.to_vec(),
        }) {
            error!("failed to send WriteConfig: {}", e);
        }
    }

    fn activate(
        &mut self,
        mem: GuestMemory,
        interrupt: Interrupt,
        queues: Vec<Queue>,
        queue_evts: Vec<EventFd>,
    ) {
        if queues.len() != QUEUE_SIZES.len() || queue_evts.len() != QUEUE_SIZES.len() {
            panic!(
                "queues ({}) or queue_evts ({}) wrong size",
                queues.len(),
                queue_evts.len()
            );
        }

        let (self_kill_evt, kill_evt) = match EventFd::new().and_then(|e| Ok((e.try_clone()?, e))) {
            Ok(v) => v,
            Err(e) => {
                panic!("failed creating kill EventFd pair: {}", e);
            }
        };
        self.kill_evt = Some(self_kill_evt);

        let (ours, theirs) = UnixSeqpacket::pair().expect("pair failed");

        if let Err(e) = self.socket.send(Request::Activate {
            shm: MaybeOwnedFd::new_borrowed(&mem),
            interrupt: MaybeOwnedFd::new_borrowed(&theirs),
            interrupt_resample_evt: MaybeOwnedFd::new_borrowed(interrupt.get_resample_evt()),
            queues,
            queue_evts: queue_evts
                .iter()
                .map(|e| MaybeOwnedFd::new_borrowed(e))
                .collect(),
        }) {
            panic!("failed to send Activate: {}", e);
        }

        let socket = Arc::clone(&self.socket);
        let worker_result = thread::Builder::new()
            .name("virtio_wl".to_string())
            .spawn(move || {
                Worker::new(socket, interrupt, MsgSocket::new(ours)).run(kill_evt);
            });

        match worker_result {
            Err(e) => {
                panic!("failed to spawn virtio_wl worker: {}", e);
            }
            Ok(join_handle) => {
                self.worker_thread = Some(join_handle);
            }
        }
    }

    fn reset(&mut self) -> bool {
        if let Err(e) = self.socket.send(Request::Reset) {
            error!("failed to send Reset: {}", e);
            return false;
        }

        match self.socket.recv() {
            Ok(Response::Reset(result)) => result,
            response => {
                error!("bad response to Reset: {:?}", response);
                false
            }
        }
    }

    fn get_device_bars(&mut self, address: PciAddress) -> Vec<PciBarConfiguration> {
        if let Err(e) = self.socket.send(Request::GetDeviceBars(address)) {
            panic!("failed to send GetDeviceBars: {}", e);
        }

        match self.socket.recv() {
            Ok(Response::GetDeviceBars(bars)) => bars,
            response => {
                panic!("bad response to GetDeviceBars: {:?}", response);
            }
        }
    }

    fn get_device_caps(&self) -> Vec<Box<dyn PciCapability>> {
        if let Err(e) = self.socket.send(Request::GetDeviceCaps) {
            panic!("failed to send GetDeviceCaps: {}", e);
        }

        match self.socket.recv() {
            Ok(Response::GetDeviceCaps(caps)) => caps
                .into_iter()
                .map(|cap| Box::new(cap) as Box<dyn PciCapability>)
                .collect(),
            response => {
                panic!("bad response to GetDeviceCaps: {:?}", response);
            }
        }
    }
}